1. Field of the Invention
The present invention relates to a direction-recognizing apparatus and a direction-recognizing method, in which a direction-indicating member recognizes a direction from an image input to it. The invention relates to a direction-recognizing system, too, which comprises a direction-indicating member and a direction-recognizing apparatus. The invention also relates to a robot apparatus that has a direction-recognizing apparatus.
2. Description of the Related Art
Any apparatus that is electrically or magnetically drive to move like a man (animal) is called “robot.” It is in 1960s that robots came into wide use. Most of them were industrial robots such as manipulators and transportation robots, which are designed to achieve automation or to save labor.
Recently, so-called “service robots” have been developed. They are designed to act as living partners to people, assisting and supporting people in social life and daily life. Unlike industrial robots, service robots are able to learn how to respond to the human friends who differ in personality, in various ways in accordance with the specific conditions in which the human partners are living. Of the service robots hitherto developed, so-called “pet-type robots” that look and act like a four-legged animal (e.g., dog or cat) and so-called “humanoid robots” that look, walk and act like man have been put to practical use.
Unlike industrial robots, pet-type robots and humanoid robots can act to entertain their human friends. This is why they are called “entertainment robots” in some cases. Some entertainment robots have various sensors such as a CCD (Charge-Coupled Device) camera, a microphone and the like. They recognize the conditions of their environment by using the sensors and autonomously act in accordance with the environmental conditions they have recognized.
The entertainment robot is designed to perform various intelligent activities. For example, the robot recognizes the user's face, finds and avoids an obstacle, and finds and approaches an object. Some entertainment robots can identify its own position from the images that the camera has acquired and which show landmarks or the like. A position-detecting apparatus that enables a robot to recognize its position is disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 10-109290. This position-detecting apparatus determines the position of the robot from the positional relation between three landmarks (e.g., three balls of different colors) placed in the region where the robot may walk around.
This method needs a plurality of landmarks in order to detect the position of the robot. In addition, the positional relation between the landmarks must be recognized to determine the position of the robot. If one landmark, for example, cannot be found, it is no longer possible to detect the position of the robot correctly. Since all landmarks must be recognized, it inevitably takes a long time to detect the position of the robot. Further, it is necessary to place a plurality of landmarks in the region in which the robot may walk. In view of this, the position-detecting method is not fit for use in entertainment robots.